Process for delustering synthetic ribbon yarns

ABSTRACT

A continuous process for delustering synthetic ribbon yarn comprising heating the yarn, contacting the yarn with an abraiding medium, and thereafter contacting the yarn with a second abraiding medium while maintaining predetermined tensions in said yarn as it first contacts, passes between, and leaves said abraiding media.

United States Patent Herbert Barber;

Howard Irving Freeman, both of Waynesboro, Va.

May 21, 1968 July 27 197 l Thiokol Chemical Corporation Bristol, Pa.

Inventors Appl. No. Filed Patented Assignce PROCESS FOR DELUSTERING SYNTHETIC RIBBON YARNS 6 Claims, I Drawing Fig.

Int. Cl D04h 17/10 Field of Search. ,....28/67, 71.3, 71.4; 57/555; 264/290, 210 F, 162,290 T, 290 R [56] References Cited UNITED STATES PATENTS 2,244,333 6/1941 Hanse 28/67 X 3,009,231 11/1961 Kleekamm et a1. 28/71.3 3,154,807 11/1964 Muller etal. 264/290 UX 3,379,807 11/1968 McIntosh et a1. 28/67 X 3,412,192 11/1968 Clapson 264/290 3,499,195 3/1970 Wethington 28/67 Primary ExaminerMervin Stein Assistant Examiner- Leo Millstein Atlorne vThomas W. Brennan ABSTRACT: A continuous process for delustering synthetic ribbon yarn comprising heating the yarn, contacting the yarn with an abraiding medium, and thereafter contacting the yarn with a second abraiding medium while maintaining predetermined tensions in said yarn as it first contacts, passes between, and leaves said abraiding media.

PATENTEU JULZTIHYI 3, 594,881

INVENTORS HERBERT BARBER HOWARD I. FREEMAN ATTORNEY PROCESS FOR DELUSTERING SYNTHETIC RIBBON YARNS This invention relates to a process for treating synthetic ribbon yarns to decrease the gloss by increasing the surface dispersion of light. In particular, the invention is applicable to a process for delustering polyolefin yarns such as ribbon made from polypropylene.

The necessity of further treatment of a surface of synthetic yarns has long been recognized. These yarns when extruded tend to form a hard, glossy outer surface which is not desirable because there will not be adequate surface friction between yarns to make a satisfactory weave, and because the woven material will have an unattractive sheen or gloss. An example of an early prior art method for delustering rayon monofilament is shown in U.S. Pat. No. 2,244,333 issued to W.C. Hanse on June 3, l94l. Later methods are illustrated by U.S. Pat. Nos. 3,l40,526 and 3,229,347 which were both issued to AJ. Tlamicha. These three patents are typical of the prior art and each shows a monofilament which is drawn over an abraiding surface so that either angular striations are made in the surface of the monofilament or so that a random roughening of the surface takes place. However, none of these prior art processes can be satisfactorily applied to flat ribbon yarn. Also, none of the prior art methods adequately teach the use of the critical parameters of yarn tension, temperature, speed, and roughness of the abraiding surface. Therefore, it is an object of the present invention to overcome these deficiencies in the prior art and to provide a method of delustering flat ribbon yarn made from synthetic material which can be performed at an economical speed.

It is another object of the present invention to provide a method to uniformly deluster flat, synthetic ribbon yarn.

lt is another object of the present invention to provide a method for delustering ribbon yarn which avoids breakage of the yarn.

These and other objects are accomplished by the present invention which is a continuous process for delustering synthetic ribbon yarn which comprises, the yarn contacting an abraiding medium on one side, and subsequently contacting an abraiding medium on the other side while maintaining predetermined tensions in the yarn as it first contacts, passes between, and leaves; said abraiding media. The application of this method produces a delustered ribbon yarn which has uniform, minute, relatively parallel, indented striations which are formed only on the surface of the ribbon.

The present invention may be better appreciated by reference to the following detailed description and the drawing which is a schematic representation of the process of the invention.

As used herein the term ribbon" means a synthetic monofilament having a width to thickness ratio of at least 5 to. l and usually 30 to l to 50 to l or greater. For example, a ribbon 0.l inches wide and 0.002 inches thick would have a width to thickness ratio of 50 to l.

The term gloss" as used herein means specular gloss measured at 60 according to ASTM method D523. Gloss is given in numerical units inversely proportional to the degree of dispersion of the light reflected from the surface under consideration. The higher the gloss the higher the numerical value.

The term synthetic when used herein and applied to ribbon yarn encompasses all synthetic or manmade materials such as plastics, rubber, or the like as contrasted to natural fiber such as wool, cotton, or silk. Plastic includes thermosetting and thermoplastic materials, particularly polyamides, polyesters, and the polyolefins such as polypropylene and polyethylene.

The term mesh" when used herein designates the size of the particles on an abraiding surface. The size is determined according'to ASTM-El l-6l.

Referring now to the drawing ribbon l is seen entering from the left and being fed over feed roll 2. From feed roll 2 the ribbon passes between heating elements 3, under the first striating or abraiding medium 4, over the second abraiding or striating medium 5, and then to feed roll 6.

Before entering the feed roll 2 the ribbon is heated to soften it and to make it more pliable but the heating temperature is kept below the flow or melting point of the material. The ribbon is kept under constant tension as it is fed to feed roll 2.

Feed roll 2 is driven to maintain tension and to regulate the speed of the yarn. The tension in the yarn is kept greater in the yarn as it leaves the feed roll 2 than it was before entering the feed roll.

Heaters 3 serve to maintain the temperature of the yarn and keep it uniformly heated. The heaters do not heat the ribbon appreciably beyond the ribbon's initial heating before it entered the roll 2.

After leaving the heaters 3 the ribbon 1 passes under striating medium 4. Striating medium 4 can be a stationery abraiding surface or it can be a rotatable cylinder with an abraiding surface. The cylinder can be made to rotate either with or against the direction of travel of the yarn l as long as a relative speed difference exists. The mesh of the particles on the abrasive surface should be in the range of 50 to 500 mesh. Also, striating medium 4 may be either heated or cooled as desired.

Ribbon yarn 1 next passes over abraiding medium 5 which can be constructed similarly to abraiding medium 4. By passing under medium 4 and over medium 5 both surfaces of the ribbon become finely striated.

Upon leaving striating medium 5 the ribbon yarn passes to feed roll 6. The relative speeds of feed roll 6 and feed roll 2 can be adjusted to both stretch and add tension to ribbon 1. It has been found that the tension maintained between feed roll sion of the yarn before it enters feed roll 2. For the present invention this has been found to be 200 to 8,000 lbs./in. ln

order to induce stretching and maintain such tension feed roll 6 should be driven so that the linear velocity of the ribbon passing thereover is in the range of 1.01 and H0 times the linear velocity of the yarn passing over the feed roll 2.

The applicability of the foregoing described process is demonstrated by the following example in which a polypropylene ribbon 0.500 inches wide and 0.002 inches thick was delustered at different tension ratios. An abrasive surface having a 240 mesh was used for both of the striating media. The initial gloss of the ribbon yarn before delustering is in the range of 50 to gloss units. The result is set forth in the following table:

The temperature entering in the above table is taken as the yarn approaches speed roll 2 and the temperature leaving is taken as the yarn leaves roll 6. Tension entering is taken as the tension in the yarn before it enters feed roll 2 and the tension during treatment is taken as the tension between speed roll 2 and speed roll 6. The speed ratio is the ratio of the linear velocity of the yarn as it passes over feed roll 6 to the velocity of the yarn as it passes over speed roll 2.

Polypropylene has a melting point in the range between 335 F. and 345 F. The polypropylene ribbon in the above example was heated to within about 60 of the melting point; and, a preferable heating range is between 240 F. and 300 F. For thermoplastic ribbons generally, the pliability of the ribbon increases with temperature thus affecting the relative feed roll velocities necessary to indure the desired tension.

it has been found that for polypropylene ribbon yarns the desirable mesh of the abraiding surface is in the range of 200 to 300 mesh.

lt is our discovery that the method of our invention with the specific conditions applied as set forth hereinabove produces a unique delustered synthetic yarn. Our invention is limited only by the scope of the followingclaims.

We claim 1. A method for treating continuously moving, synthetic ribbon yarn to lower its gloss or luster comprising the steps of:

a. heating the yarn;

b. increasing the tension in said heated yarn, said tension increase obtained by increasing the linear velocity of said moving yarn l.Ol to LlOtimes;

c. contacting one surface of the ribbon yarn with a first striating medium; and subsequently,

d. contacting the other surface of said yarn with a second striating medium.

4. The method of claim 1 wherein the synthetic yarn is stretched as it contacts said striating media.

5. The method of claim 1 wherein the synthetic yarn is polypropylene and is heated in a temperature range of from 260 to 300 F.

6. The method of claim 4 wherein the tension in said ribbon yarn is maintained in the range of between 2,000 and 8,000 lbs. per sq. inch while said yarn contacts said striating media. 

2. The method of claim 1 wherein the tension in said yarn is increased one to four times prior to its contacting said striating medium.
 3. The method of claim 2 wherein the tension is in the range of 2,000 to 8,000 p.s.i.
 4. The method of claim 1 wherein the synthetic yarn is stretched as it contacts said striating media.
 5. The method of claim 1 wherein the synthetic yarn is polypropylene and is heated in a temperature range of from 260 to 300* F.
 6. The method of claim 4 wherein the tension in said ribbon yarn is maintained in the range of between 2,000 and 8,000 lbs. per sq. inch while said yarn contacts said striating media. 